1 files changed, 27 insertions, 15 deletions
diff --git a/app/graphql/types/global_id_type.rb b/app/graphql/types/global_id_type.rb
index ed28c3ffd7e..750bd1bfe8d 100644
--- a/app/graphql/types/global_id_type.rb
+++ b/app/graphql/types/global_id_type.rb
@@ -19,7 +19,14 @@ end
 module Types
   class GlobalIDType < BaseScalar
     graphql_name 'GlobalID'
-    description 'A global identifier'
+    description <<~DESC
+      A global identifier.
+
+      A global identifier represents an object uniquely across the application.
+      An example of such an identifier is "gid://gitlab/User/1".
+
+      Global identifiers are encoded as strings.
+    DESC
 
     # @param value [GID]
     # @return [String]
@@ -46,35 +53,40 @@ module Types
 
       @id_types[model_class] ||= Class.new(self) do
         graphql_name "#{model_class.name.gsub(/::/, '')}ID"
-        description "Identifier of #{model_class.name}."
+        description <<~MD
+          A `#{graphql_name}` is a global ID. It is encoded as a string.
+
+          An example `#{graphql_name}` is: `"#{::Gitlab::GlobalId.build(model_name: model_class.name, id: 1)}"`.
+        MD
 
-        self.define_singleton_method(:to_s) do
+        define_singleton_method(:to_s) do
           graphql_name
         end
 
-        self.define_singleton_method(:inspect) do
+        define_singleton_method(:inspect) do
           graphql_name
         end
 
-        self.define_singleton_method(:coerce_result) do |gid, ctx|
+        define_singleton_method(:coerce_result) do |gid, ctx|
           global_id = ::Gitlab::GlobalId.as_global_id(gid, model_name: model_class.name)
 
-          if suitable?(global_id)
-            global_id.to_s
-          else
-            raise GraphQL::CoercionError, "Expected a #{model_class.name} ID, got #{global_id}"
-          end
+          next global_id.to_s if suitable?(global_id)
+
+          raise GraphQL::CoercionError, "Expected a #{model_class.name} ID, got #{global_id}"
         end
 
-        self.define_singleton_method(:suitable?) do |gid|
-          gid&.model_class&.ancestors&.include?(model_class)
+        define_singleton_method(:suitable?) do |gid|
+          next false if gid.nil?
+
+          gid.model_name.safe_constantize.present? &&
+            gid.model_class.ancestors.include?(model_class)
         end
 
-        self.define_singleton_method(:coerce_input) do |string, ctx|
+        define_singleton_method(:coerce_input) do |string, ctx|
           gid = super(string, ctx)
-          raise GraphQL::CoercionError, "#{string.inspect} does not represent an instance of #{model_class.name}" unless suitable?(gid)
+          next gid if suitable?(gid)
 
-          gid
+          raise GraphQL::CoercionError, "#{string.inspect} does not represent an instance of #{model_class.name}"
         end
       end
     end